The Presence of Ribulose 1,5-Diphosphate Carboxylase in the Nonphotosynthetic Endosperm of Germinating Castor Beans
- 1 April 1973
- journal article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 51 (4), 755-759
- https://doi.org/10.1104/pp.51.4.755
Abstract
Ribulose 1,5-diphosphate carboxylase was detected in extracts of germinating castor bean (Ricinus communis var. Hale) endosperms. This is the first report of this enzyme in a nonphotosynthetic (no chlorophyll) plant tissue. Radioactive 3-phosphoglyceric acid has been identified as the principle product resulting from the enzymatic condensation of 14C-bicarbonate and ribulose-1,5-diP in endosperm extracts. The Km values of bicarbonate and ribulose-1,5-diP for the endosperm carboxylase are 1.14 × 10−2m and 7.5 × 10−5m, respectively. The carboxylase activity peaks at 4 days in endosperms of castor beans germinated in the dark. The specific activity of the carboxylase at this stage of germination is 4.3 μmoles of 3-phosphoglycerate formed/mg protein·hr. The presence of ribulose-1,5-diP carboxylase and other enzymes of the reductive pentose phosphate pathway show the potential of this pathway in castor bean endosperms.Keywords
This publication has 10 references indexed in Scilit:
- GLYOXYSOMES OF CASTOR BEAN ENDOSPERM AND THEIR RELATION TO GLUCONEOGENESIS*Annals of the New York Academy of Sciences, 1969
- Enzyme Activities of the Carbon Reduction Cycle in Some Photosynthetic OrganismsPlant Physiology, 1969
- CO2 Metabolism in Corn Roots. III. Inhibition of P-enolpyruvate Carboxylase by l-malatePlant Physiology, 1968
- Changes in Enzymatic Activities in Etiolated Bean Seedling Leaves After a Brief IlluminationPlant Physiology, 1968
- Effects of Light Intensity on Photosynthetic Carboxylative Phase Enzymes and Chlorophyll Synthesis in Greening Leaves of Hordeum vulgare LPlant Physiology, 1966
- Formation of sucrose from malate in germinating castor beans. I. Conversion of malate to phosphoenol-pyruvatePlant Physiology, 1961
- Intracellular and Phylogenetic Distribution of Ribulose 1,5-Diphosphate Carboxylase and D-Glyceraldehyde-3-Phosphate Dehydrogenases.Plant Physiology, 1959
- The reductive pentose phosphate cycle. II. Specific C-1 phosphatases for fructose 1,6-diphosphate and sedoheptulose 1,7-diphosphateArchives of Biochemistry and Biophysics, 1958
- The oxidative pentose phosphate cycle. II. Quantitative determination of intermediates and enzymesArchives of Biochemistry and Biophysics, 1958
- The reductive pentose phosphate cycleArchives of Biochemistry and Biophysics, 1957